Handling redundant data in a communication system

ABSTRACT

Explicit discard indications are used that allows a radio network controller, when operating in a multi-point High Speed Downlink Packet Access, HSDPA, scenario, to send data to a user equipment via plural radio base stations while reducing the risk for unnecessary duplicate data to be sent over the Uu interface between the radio base stations and the user equipment.

RELATED APPLICATIONS

This application claims priority under 35 USC 120 as a continuation ofU.S. application Ser. No. 14/123,383, as filed on 2 Dec. 2013 and nowissued as U.S. Pat. No. 8,953,576, which prior application is a 371national-stage of PCT/SE2012/051179 as filed on 31 Oct. 2012, andfurther claims priority from the US provisional application filed on 4Nov. 2011 and assigned App. No. 61/556,012, and all such applicationsare incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to handling redundant data communicatedbetween different entities in a radio access network, such as radio basestations and radio network controllers.

BACKGROUND

The third generation partnership project, 3GPP, is currently working onspecifying support for MP HSDPA (Multi-Point High-Speed Downlink PacketAccess) in Release-11. When MP HSDPA is employed, downlink data is sentto UE (User Equipment, also referred to as mobile/wireless terminal) viatwo instead of one NodeB (herein also referred to as radio base station,RBS). The UE will thus receive data via two MAC-hs (HSDPA Medium AccessControl protocol handling fixed size RLC data) or MAC-ehs (HSDPA MediumAccess Control protocol handling fixed or flexible sized RLC data) flowsand re-order data on RLC (Radio Link Control) level for delivery tohigher layers. It should be noted that various terminology has been usedto describe this functionality in 3GPP such as HSDPA MultipointTransmission, Inter-NodeB Multi-Point Transmissions and HSDPA Multiflowdata but the abbreviation MP HSDPA will henceforth be used to describethis functionality.

A potential problem with some existing MP HSDPA solutions is that sincedata in the UE may be received from more than one NodeB, then the dataas delivered to the RLC layer in UE may be out of order. Since the RLClayer in UE will trigger a status report when missing RLC SN (SequenceNumber) is detected, this will lead to unnecessary RLC retransmissionsif the missing data has already been sent to the other NodeB but not yettransmitted to UE. The unnecessary retransmissions this will cause willin turn result in that one or both NodeBs will buffer and eventuallytransmit redundant data to the UE.

Various solutions to this problem on RLC level have been suggested asoutlined in 3GPP reference R2-113299, “Layer 2 considerations forInter-Node Multipoint HSDPA operation”, but these may notreduce/eliminate the problem of redundant data. To this it can be addedthat in a MP HSDPA there may even be multiple copies of the same MAC-d(Medium Access Control protocol handling dedicated data) PDUs (ProtocolData Units) in one or both NodeB PQs (Priority Queues) since the UE mayvia RLC status reports sent requests for additional retransmissions fordata already queued in the NodeB but not yet transmitted.

Although this may not necessarily cause a protocol failure, it isdetrimental in that it can lead to an inefficient use of available airinterface resources in existing solutions because this redundant datamay need to be sent to UE before it is discarded.

SUMMARY

In order to enable a more efficient use of air interface resources,there are provided methods, apparatuses and computer program products inseveral aspects. Hence, there is provided in a first aspect of theinvention a method in a radio network controller. The radio networkcontroller is configured for multi-point HSDPA operation wherein data iscommunicated to a first user equipment via at least two radio basestations. The method comprises transmitting a discard indication signalto at least one of the at least two radio base stations. The discardindication signal includes a first data frame sequence number. Thediscard indication signal indicates to the at least one radio basestation that MAC-d PDUs received by the at least one radio base stationfrom the radio network controller in a data frame associated with thefirst data frame sequence number can be discarded.

In a second aspect of the invention there is provided a method in aradio base station. The radio base station is configured to participatein multi-point HSDPA operation wherein data is communicated to a firstuser equipment via the radio base station and at least one other radiobase station. The method comprises receiving MAC-d PDUs from a radionetwork controller in data frames, wherein each data frame conveyingMAC-d PDUs is associated with a sequence number. The received MAC-d PDUsare buffered in a buffer pending transfer to the first user equipment. Adiscard indication signal is received from the radio network controller.The received discard indication signal includes a data frame sequencenumber and the discard indication signal indicates to the radio basestation that MAC-d PDUs received by the radio base station in a dataframe associated with said sequence number can be discarded.

In a third aspect of the invention there is provided a radio networkcontroller. The radio network controller is configurable for multi-pointHSDPA operation wherein data is communicated to a first user equipmentvia at least two radio base stations. The radio network controllercomprises digital data processing circuitry adapted to generate adiscard indication signal for transmission to at least one of the atleast two radio base stations. The discard indication signal includes afirst data frame sequence number and the discard indication signalindicates to the at least one radio base station that MAC-d PDUsreceived by the at least one radio base station from the radio networkcontroller in a data frame associated with the first data frame sequencenumber can be discarded. The radio network controller further comprisesa transmitter operable connected to the digital data processingcircuitry. The transmitter is adapted to transmit the generated discardindication signal to the at least one of the at least two radio basestations.

In a fourth aspect of the invention there is provided a radio basestation. The radio base station is configurable to participate inmulti-point HSDPA operation wherein data is communicated to a first userequipment via the radio base station and at least one other radio basestation. The radio base station comprises a receiver arranged to receiveMAC-d PDUs from a radio network controller in data frames, wherein eachdata frame conveying MAC-d PDUs is associated with a sequence number.The radio base station further comprises digital data processingcircuitry that is operable connected to the receiver and arranged tobuffer the received MAC-d PDUs in a buffer pending transfer to the firstuser equipment. The receiver is further arranged to receive a discardindication signal from the radio network controller. The discardindication signal includes a data frame sequence number and the discardindication signal indicates to the radio base station that MAC-d PDUsreceived by the radio base station in a data frame associated with saidsequence number can be discarded.

In a fifth aspect of the invention there are provided non-transitorycomputer program products comprising software instructions that areconfigured, when executed in a processor, to perform the method of thefirst and second aspects.

That is, embodiments of the invention make use of an explicit discardindication that allows the radio network controller, when operating in aMP HSDPA scenario, to send data to a user equipment via plural radiobase stations while reducing the risk for unnecessary duplicate data tobe sent over the Uu interface. Since the capacity to convey data viadifferent radio base stations varies over time due to variations in boththe transport network and radio conditions, it may be advantageous ifretransmissions can be done over the radio base station link that hasthe greatest capacity at the time of retransmission. With such discardindications, redundant copies of MAC-d PDUs can be discarded beforetransmission over the Uu interface thereby saving Uu bandwidth.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates schematically a mobile communication system,

FIG. 2 illustrates schematically a radio base station,

FIG. 3 illustrates schematically a radio network controller,

FIGS. 4 and 5 are flow charts of methods embodying the invention,

FIGS. 6 to 11 illustrate schematically content of data frames used forcommunication between entities in a mobile communication system.

DETAILED DESCRIPTION

FIG. 1 illustrates schematically a mobile communication system in theform of a cellular network 100 in which the present methods andapparatuses can be implemented. The cellular network 100 in FIG. 1 isexemplified by a universal mobile telecommunications system, UMTS. Itshould be noted, however, that the skilled person will readily be ableto perform implementations in other similar communication systemsinvolving transmission of coded data between nodes.

In FIG. 1 the cellular network 100 comprises a core network 102 and aUMTS terrestrial radio access network, UTRAN, 103. The UTRAN 103comprises a number of nodes in the form of radio network controllers,RNC, 105 a, 105 b, each of which is coupled via a so-called transportnetwork, TN, 112, to a set of neighbouring nodes in the form of one ormore NodeB 104 a, 104 b, 104 c. Each NodeB 104 is responsible for agiven geographical radio cell and the controlling RNC 105 is responsiblefor routing user and signaling data between that NodeB 104 and the corenetwork 102. All of the RNCs 105 are coupled to one another. Signalingbetween the NodeBs and the RNCs includes signaling according to the lubinterface. A general outline of the UTRAN 103 is given in 3GPP technicalspecification TS 25.401 V3.2.0.

FIG. 1 also illustrates communicating entities in the form of mobiledevices or user equipment, UE, 106 a, 106 b and radio base stations inthe form of NodeBs 104 a, 104 b, 104 c. A first UE 106 a communicateswith a first NodeB 104 a via an air interface 111 and a second UE 106 bcommunicates with the first NodeB 104 a and with a second NodeB 104 bvia the air interface 111. Signaling in the air interface 111 includessignaling according to the Uu interface. As will be elucidated in somedetail below, the UEs 106 b operates by utilizing MP-HSDPA in relationto the two NodeBs 104 a and 104 b.

The core network 102 comprises a number of nodes represented by node 107and provides communication services to the UEs 106 via the UTRAN 103,for example for communication between UEs connected to the UTRAN 103 orother mobile or fixed networks and when communicating with the Internet109 where, schematically, a server 110 illustrates an entity with whichthe mobile devices 106 may communicate. As the skilled person realizes,the network 100 in FIG. 1 may comprise a large number of similarfunctional units in the core network 102 and the UTRAN 103, and intypical realizations of networks, the number of mobile devices may bevery large.

FIG. 2 is a functional block diagram that schematically illustrates anexample of a radio network controller, RNC, 200 that is configured tooperate in a radio access network, such as the UTRAN 103 in FIG. 1. Inthe embodiment of FIG. 2, the RNC 200 represents a RNC, such as any ofthe RNCs 105 in FIG. 1.

The RNC 200 comprises digital data processing circuitry comprisingprocessing means, memory means and communication means in the form of aprocessor 202, a memory 204 and communication circuitry 206 thatincludes a transmitter 216 capable of transmitting data to otherentities in the network. For example, the circuitry of these means 202,204 and 206 can comprise and/or form part of one or more applicationspecific integrated circuit, ASIC, as well as one or more digital signalprocessor, DSP. The RNC 200 receives data 212 via an incoming data path210 and transmits data 214 via an outgoing data path 208. The data 210,212 can be any of uplink and downlink data, as the skilled person willrealize.

Methods to be described below can be implemented in the RNC 200. In suchembodiments, the method actions are realized by means of softwareinstructions 205 that are stored in the memory 204 and are executable bythe processor 202. Such software instructions 205 can be realized andprovided to the RNC 200 in any suitable way, e.g. provided via thenetworks 102, 103 or being installed during manufacturing, as theskilled person will realize. Moreover, the memory 204, the processor202, as well as the communication circuitry 206 comprise software and/orfirmware that, in addition to being configured such that it is capableof implementing the methods to be described, is configured to controlthe general operation of the RNC 200 when operating in a communicationsystem such as the system 100 in FIG. 1. However, for the purpose ofavoiding unnecessary detail, no further description will be made in thepresent disclosure regarding this general operation.

FIG. 3 is a functional block diagram that schematically illustrates anexample of a radio base station, RBS, in the form of a NodeB 300,corresponding to any of the NodeBs 106 in FIG. 1. The NodeB 300comprises radio frequency, RF, receiving and transmitting circuitry 306,an antenna 307 and digital data processing circuitry comprising aprocessor 302, a memory 304, and communication circuitry 308. The memory304 comprises a buffer 311 for buffering data that is communicated withother entities. For example, the buffer 311 can hold MAC-PDUs in apriority queue as will be discussed in more detail below. Thecommunication circuitry 308 includes a receiver 313 capable of receivingdata from other entities in the network. Radio communication via theantenna 307 is realized by the RF circuitry 306 controlled by theprocessor 302, as the skilled person will understand. The circuitry ofthese means 302, 304, and 308 can comprise and/or form part of one ormore application specific integrated circuit, ASIC, as well as one ormore digital signal processor, DSP. The processor 302 makes use ofsoftware instructions 305 stored in the memory 304 in order to controlfunctions of the NodeB 300, including the functions to be described indetail below with regard to handling of PDUs. In other words, at leastthe communication circuitry 308, the processor 302 and the memory 304form parts of digital data processing and communication circuitry thatis configured to handle PDUs as summarized above and described in detailbelow. Further details regarding how these units operate in order toperform normal functions within a communication system, such as thesystem 100 of FIG. 1, are outside the scope of the present disclosureand are therefore not discussed further.

Turning now to FIGS. 4 and 5, and with continued reference to theprevious figures, examples of methods associated with discarding of PDUswill be described in some more detail.

FIG. 4 describes a method in a RNC, such as any of the RNCs 105 in FIG.1 and the RNC 200 in FIG. 2. FIG. 5 describes a method in a radio basestation, RBS, or NodeB, such as a NodeB as illustrated by the NodeBs 104in FIG. 1 and the NodeB 300 in FIG. 3. The methods of FIGS. 4 and 5describe behaviour in separate interrelated products that facilitate adiscard of redundant data queued in a NodeB before transmission over theair interface. In a MP HSDPA scenario (i.e. involving at least twoNodeBs) there may due to RLC retransmissions be data in one or bothNodeBs that is redundant since it has already been received by UE. Itshould be noted that there may even be multiple copies of the same MAC-dPDUs in one or both NodeB PQs since the UE may via status reports sendrequests for additional retransmissions for data already queued in theNodeB but not yet transmitted. As soon a the UE has received this datavia either NodeB, all other copies are redundant and could preferably becleared from the PQs in order to make room for transmission of data thatUE has yet not received.

By keeping track of what data has been sent in which TN (TransportNetwork) frame type 1 or 2 and by monitoring the RLC status reports sentby UE, the RNC knows when the UE has received which data and what datais therefore still in the NodeB awaiting transmission. Based on thisinformation the RNC will thus know when to send discard indications tothe NodeB. These discard indications may either be carried in new dataor control frames scheduled for transmission or sent in dedicated framesdevoid of data if no data is scheduled for transmission, as will beexemplified in more detail below. Since the RNC via the RLC statusreports knows that the UE has received the data but is unaware of viawhich NodeB, the discard indication can be sent to one or more of theNodeBs. The NodeB in turn reads the discard indication from the RNC andif such data is stored discards this. It should be noted that the RNCcan keep track of to which NodeB data has been sent and only send thediscard indication to the NodeB who has the redundant data.

FIG. 4 illustrates a method in a radio network controller according toan embodiment of the invention. The radio network controller isconfigured for MP-HSDPA operation wherein data is communicated to afirst user equipment via at least two radio base stations. At step 402,a decision is made whether a discard indication signal should be sent.This decision may be based on the radio network controllers knowledge ofwhich data has been received by the first user equipment derived frommonitoring of RLC status reports sent by the first user equipment andproviding acknowledgement status of RLC PDU's (where each RLC PDUcorresponds to one MAC-d PDU). In a scenario where more than one MAC-dPDUs (and consequently more than one RLC PDU) may have been sent in adata frame, the decision may also be based on the radio networkcontrollers knowledge of what data (i.e. MAC-d PDUs/RLC PDUs) have beensent in which data frame i.e. transport network frame. Hence, thedecision whether a discard indication signal should be sent may be basedon the radio network controllers knowledge of which data the UE hasreceived and which data is still awaiting transmission derived bymonitoring the RLC status reports sent by the first user equipment andkeeping track of which data have been sent in which data frame.

If a discard indication should be sent (alternative “YES” at step 402),a discard indication signal is transmitted in a transmission step 404 toat least one of the at least two radio base stations. The discardindication signal includes a first data frame sequence number andindicates to the at least one radio base station that MAC-d PDUsreceived by the at least one radio base station from the radio networkcontroller in a data frame associated with the first data frame sequencenumber can be discarded.

FIG. 5 illustrates a method in a radio base station (or NodeB) accordingto an embodiment of the invention. The radio base station is configuredto participate in MP HSDPA operation wherein data is communicated to afirst user equipment via the radio base station and at least one otherradio base station. Data is received, in a reception step 502, from theradio network controller. The received data is in the form of MAC-d PDUsin data frames, wherein each data frame conveying MAC-d PDUs isassociated with a sequence number. The received MAC-d PDUs are buffered,in a buffering step 504, in a buffer pending transfer to the first userequipment. A discard indication signal is received, in a reception step506, from the radio network controller. The discard indication signalincludes a data frame sequence number and wherein the discard indicationsignal indicates to the radio base station that MAC-d PDUs received bythe radio base station in a data frame associated with said sequencenumber can be discarded. At discard step 508, any MAC-d PDU still in thebuffer and associated with said data frame sequence number in thediscard indication signal may be discarded.

There are many different ways to indicate data to be discarded to theNodeB. That is, examples of how the discard indication signal can berealized will now be described with reference to FIGS. 6 to 11, wherethe examples include the use of reserved bits or assigning new meaningto already existing fields or defining new IE (Information Element) ineither data or control frames of the type 1 and 2 HS-DSCH (High-SpeedDownlink Shared Channel) Frame Protocol (FP). FIGS. 6 to 11 illustrateframe fields that are graphically emphasized by being hashed. Typically,in the following, the fields that are discussed in detail are those thatare emphasized.

It should be noted that it may not be possible for the NodeB to discardall MAC-d PDUs as indicated in the discard message since some MAC-d PDUsmay be partially transmitted or in the process of being transmitted. Insome embodiments partially transmitted MAC-d PDUs and data moved fromthe NodeB PQ but still awaiting transmission on MAC-hs or MAC-ehs layerin the NodeB are excluded from deletion while in other embodiments alsothese MAC-d PDUs are discarded.

For example, a new sequence number, SN, specially related to the discardfunctionality is sent in every frame by utilizing the 15 of the 16 bitsreserved to indicate “User Buffer Size” for this purpose.

In order to distinguish from the legacy use, the bit “0” in octet 4reserved in both type 1 and type 2 FP is used. If the value of this bitis “0” then the legacy definition as “User Buffer Size” applies.

If this bit is set to “1” instead, then the NodeB shall interpret thisas an indication that all the 8 bits in octet 6 and bits 1 to 7 in octet7 for type 1 FP indicate a SN. The last bit “0” in octet 7 is used toindicate how the NodeB shall interpret and use the associated SN. Ifthis bit is set to “1” then the NodeB shall store all MAC-d PDUs incontained in the frame and associate these with the SN. If this bit isset to “0”, then the NodeB shall discard all MAC-d PDUs associated withthis SN. Note that for type 2 FP then the mapping is the same but octet5 and 6 carry the “User Buffer Size” field.

This example provides an advantage in that the SN space is 32767 whichin practice eliminates the risk of SN wrap around. Note that a solutionusing less of the 16 bits in the “User Buffer Size” is also possible butthat this may lower the margin against SN wrap around. However, even ifthere in practice is no risk of a wrap around, it is of course stillpossible to implement a timer based flush as well that clears all storeddata at timer expiry. An additional enhancement is to use another of the16 bits in the “User Buffer Size” field to indicate that all data in PQshould be discarded. One possible embodiment in this case is again touse the last bit “0” in octet 4 reserved in both type 1 and type 2 FP.If the value of this bit is “0” then the legacy definition as “UserBuffer Size” for octets 6 and 7 applies for type 1 FP. If this bit isset to “1” instead, then in this case the NodeB shall interpret this asan indication that all the 8 bits in octet 6 and bits 2 to 7 in octet 7indicate a SN for type 1 FP. This means that the SN space is reducedfrom 15 to 14 bits and the freed bit “1” would then be used to indicatethat all buffered data is to be discarded if this is set to “1” or inthe case that this bit is set to “0” indicate that the SN should be readand only data associated with this SN discarded. Note that for type 2 FPthen the mapping is the same but octet 5 and 6 carry the “User BufferSize” field.

Note that it is also possible to indicate discard even though no data isscheduled for transmission. In this scenario the RNC sends a frame withthe same SN as previously sent but in this case containing no data butcontain the discard indication as outlined above. For FP type 1, thevalue “0” to “NumOfPDU” is introduced to indicate that no data iscontained in frame since range of is limited to 1-255 in current versionof standard. For FP type 2 it is already possible with the currentstandard to indicate that no data is contained since range of “TotalNumber of PDU blocks” is 0-31.

In another example, the “New IE Flags” field is used to introduce the SNand indicate data to discard. This will in the following be illustratedby reference to 3GPP TS 25.435, V10.3.0 (2011-09) and how the coding ofIEs can be modified in order to accommodate such examples.

With reference to FIG. 21A in 3GPP TS 25.435, V10.3.0, bit 1 of New IEFlags in HS-DSCH DATA FRAME TYPE1 indicate if a SN is present (1) or not(0) in the third and the fourth octets following the New IE Flags IE.Bit 0 in the fourth octet is allocated for IE S/D. Bits 2 through 6 ofNew IE Flags in HS-DSCH DATA FRAME TYPE 1 shall be set to 0.

Field length of Spare Extension IE in HS-DSCH DATA FRAME TYPE 1 is 0-27octets.

In terms of how the description of IE coding in 3GPP TS 25.435, V10.3.0,can be supplemented, the following addition can be made with regard tothe frame sequence number, SN: SN is a sequence number assigned to eachframe by RNC and shall be used by the NodeB to identify the set of MAC-dPDUs sent in frame. This is also used by RNC to indicate MAC-d PDUs thatthe NodeB shall discard. The value range is {0 . . . 32767} and thefield length is 15 bits.

With regard to the Store/Discard, S/D, indicator, it indicates if theNodeB shall store or discard data associated with SN. The value range is{0=Discard data associated with SN, 1=Store and associate MAC-d PDUs inframe with SN} and the field length is 1 bit.

Such changes and additions are illustrated in FIG. 6 for FP type 1 andfor FP type 2 in FIG. 7. Note that the same type of mapping using “NewIE Flags” field as exemplified above for type 1 FP can also be done fortype 2 FP but is not shown here.

Instead of using the spare bit in the FRAME TYPE header, (bit 0 in thefourth Octet), as exemplified above, it is also possible to define a newIE MP to indicate to the NodeB if the “User Buffer Size” is defined aslegacy or defined as SN. Similar change can apply to Type 2 (notillustrated).

Now with reference to FIG. 8, it is also possible to supplement the IEcoding by having bit 1 of New IE Flags in HS-DSCH DATA FRAME TYPE1indicate if a MP is present (1) or not (0) in the third octets below theNew IE Flags IE. Bits 2 through 6 of New IE Flags in HS-DSCH DATA FRAMETYPE 1 shall be set to 0. In such cases, the field length of SpareExtension IE in HS-DSCH DATA FRAME TYPE 1 is 0-28 octets.

Furthermore, the IE coding can be supplemented by the addition of an MPindicator. MP is a 1 bit indicator for Multi Point related operation. Avalue of 0 means the User Buffer Size is defined as legacy; a value of 1means the “user buffer size” is defined as SN. The value range is {0 . .. 1} and the field length is 1 bit.

Further examples include those where a HS-DSCH data frame carries bothnew data and an indication to discard data in the same frame. Hence thiswould require that two SN and indication to discard is carried in thesame frame which could be achieved e.g. by including two “New IE Flag”fields or one “New IE Flag” field in combination with the “User Buffersize” field. As an example, FIG. 9 illustrates a HS-DSCH data frame type1 including two new SN fields, in order to associate the MAC-d PDU(s) inthe current frame with the one SN, and indicate which MAC-d PDU todiscard in the NodeB with the second SN.

Still further examples include those where use is made of control framesto allow RNC to indicate to the NodeB which SN to discard. The spare bit(bits) or new IE in the capacity request can be used to indicate if theCapacity, CA, Request (HS-DSCH Capacity Request) is legacy or if it isfor discarding purpose. The SN to be discarded can be indicated eitherby reusing the existing “User Buffer Size” field or by introducing a newIE.

For example the reserved bits “4” to “7” in first octet in Capacity, CA,Request frame can be used. Currently bit “4” is set to “0”. But if thisbit is set to “1” then “User Buffer Size” in the 8 bits of the secondoctet and bit 7 to 1 of the third octets is used to carry SN to bediscarded. Or if SN is introduced as a new IE, then SN indicated in thenew SN filed should be discarded. It is interpreted by the NodeB thatMAC-d PDUs associated with the SN shall be discarded from the NodeB.

In such examples, the NodeB can be required to always associate theMAC-d PDUs stored in a type 1 or type 2 frame with the SN and store thisdata for possible future use (i.e. for discarding). The NodeB does notneed to reply back to the RNC with CA Allocation in this case toindicate to the RNC that the data has been discarded.

But it is possible if RNC wants to know that the data is discarded, thespare bits or new IE is defined in the CA Allocation (HS-DSCH CapacityAllocation) to fulfill this purpose.

An example of a HS-DSCH Capacity (CA) Request, illustrated in FIG. 10,shows that bit 4 in the first Octet is used to indicate discardingfunction.

Dis, 1 bit, if it is set to 1, then User Buffer Size is used to carry SNto be discarded.

Another example of a HS-DSCH Capacity (CA) Request involves defining anew IE SN (15 bits or any other bits) in the HS-DSCH Capacity Request asillustrated in FIG. 11.

In the example of FIG. 11, Bit 0 of New IE Flags in CA Request indicatesif SN is present (1) or not (0) in the two octets following the New IEFlags IE. Bits 1 through 6 of New IE Flags in CA Request frame shall beset to 0. Field length of Spare Extension IE in HS-DSCH Capacity Requestis 0-29 octets.

Even further examples involves letting the RNC indicate to the NodeBwhich frame to discard in the NodeB Application Part/Radio NetworkSubsystem Application Part, NBAP/RNSAP, control plane signaling, oncethe HS-DSCH data frame is associated with the SN and the NodeB hasstored the information.

A new information element identifying sequence number(s) of MAC-d frameswhich could be discarded can be added to the existing NBAP/RNSAPsignaling, for example in Radio Link Deletion Request. This way, themessage is modified so that RNC can indicate to the NodeB that thepurpose of the message is to discard the frame, and also include whichSN to discard when the NodeB receives the message.

A new signaling with the SN identifier included can also be introducedin NBAP/RNSAP so that the RNC can indicate to the NodeB which SN todiscard.

As used herein, the terms “comprise”, “comprising”, “comprises”,“include”, “including”, “includes”, “have”, “has”, “having”, or variantsthereof are open-ended, and include one or more stated features,integers, nodes, steps, components or functions but do not preclude thepresence or addition of one or more other features, integers, nodes,steps, components, functions or groups thereof.

Example embodiments are described herein with reference to blockdiagrams and/or flowchart illustrations of computer-implemented methods,apparatus (systems and/or devices) and/or computer program products. Itis understood that a block of the block diagrams and/or flowchartillustrations, and combinations of blocks in the block diagrams and/orflowchart illustrations, can be implemented by computer programinstructions that are performed by one or more computer circuits. Thesecomputer program instructions may be provided to a processor circuit ofa programmable data processing circuit to produce a machine, such thatthe instructions, which execute via the processor of the computer and/orother programmable data processing apparatus, transform and controltransistors, values stored in memory locations, and other hardwarecomponents within such circuitry to implement the functions/actsspecified in the block diagrams and/or flowchart block or blocks, andthereby create means (functionality) and/or structure for implementingthe functions/acts specified in the block diagrams and/or flowchartblock(s).

These computer program instructions may also be stored in a tangiblecomputer-readable medium that can direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer-readablemedium produce an article of manufacture including instructions whichimplement the functions/acts specified in the block diagrams and/orflowchart block or blocks.

A tangible, non-transitory computer-readable medium may include anelectronic, magnetic, optical, electromagnetic, or semiconductor datastorage system, apparatus, or device. More specific examples of thecomputer-readable medium would include the following: a portablecomputer diskette, a random access memory (RAM) circuit, a read-onlymemory (ROM) circuit, an erasable programmable read-only memory (EPROMor Flash memory) circuit, a portable compact disc read-only memory(CD-ROM), and a portable digital video disc read-only memory(DVD/BluRay).

The computer program instructions may also be loaded onto a computerand/or other programmable data processing apparatus to cause a series ofoperational steps to be performed on the computer and/or otherprogrammable apparatus to produce a computer-implemented process suchthat the instructions which execute on the computer or otherprogrammable apparatus provide steps for implementing the functions/actsspecified in the block diagrams and/or flowchart block or blocks.Accordingly, embodiments of the present invention may be embodied inhardware and/or in software (including firmware, resident software,micro-code, etc.) that runs on a processor such as a digital signalprocessor, which may collectively be referred to as “circuitry,” “amodule” or variants thereof.

Moreover, the functionality of a given block of the flowcharts and/orblock diagrams may be separated into multiple blocks and/or thefunctionality of two or more blocks of the flowcharts and/or blockdiagrams may be at least partially integrated. Finally, other blocks maybe added/inserted between the blocks that are illustrated.

Other network elements, communication devices and/or methods accordingto embodiments of the invention will be or become apparent to one withskill in the art upon review of the present drawings and description. Itis intended that all such additional network elements, devices, and/ormethods be included within this description, be within the scope of theclaims. Moreover, it is intended that all embodiments disclosed hereincan be implemented separately or combined in any way and/or combination.

Although attempt has been made in the above to explain the abbreviationswhen first introduced below follows a list of most of the abbreviationsused:

AMD Acknowledged Mode Data

FP Frame Protocol

HSDPA High Speed Downlink Packet Access

HS-DSCH High Speed Downlink Shared Channel

MAC Medium Access Control

MAC-d Medium Access Control protocol handling dedicated data

MAC-hs HSDPA Medium Access Control protocol handling fixed size RLC data

MAC-ehs HSDPA Medium Access Control protocol handling fixed or flexiblesized RLC data

MP-HSDPA Multi Point High Speed Downlink Packet Access

NBAP NodeB Application Part

PDU Protocol Data Unit

PQ Priority Queue

RLC Radio Link Control

RNC Radio Network Controller

NodeB Radio Base Station (alternatively referred to as RBS)

RNSAP Radio Network Subsystem Application Part

SN Sequence Number

TN Transport Network

UE User Equipment

WCDMA Wideband Code Division Multiple Access

What is claimed is:
 1. A method in a radio base station, said radio basestation configured to participate in multi-point High Speed DownlinkPacket Access, HSDPA, operation wherein data is communicated to a firstuser equipment via the radio base station and at least one other radiobase station, the method comprising: receiving Medium Access Controlprotocol handling dedicated data Protocol Data Units, MAC-d PDUs, from aradio network controller in data frames, wherein each data frameconveying MAC-d PDUs is associated with a sequence number; buffering thereceived MAC-d PDUs in a buffer pending transfer to the first userequipment; and receiving a discard indication signal from the radionetwork controller, wherein said discard indication signal includes adata frame sequence number and wherein the discard indication signalindicates to the radio base station that MAC-d PDUs received by theradio base station in a data frame associated with said sequence numbercan be discarded; wherein the discard indication signal is a High SpeedDownlink Shared Channel, HS-DSCH, DATA FRAME including a first dataframe sequence number and a discard flag indicating that MAC-d PDUsreceived by the at least one radio base station in the data frameassociated with the first data frame sequence number can be discarded;and wherein the HS-DSCH DATA FRAME includes a New Information Element,IE, Flags field, wherein the New IE Flags field indicates that thediscard flag and the first data frame sequence number are present in theHS-DSCH DATA FRAME and the discard flag and the first data framesequence number are included in two octets following the New IE Flagsfield.
 2. The method according claim 1, wherein when buffering thereceived MAC-d PDUs in the buffer, the association between each MAC-dPDU and the data frame sequence number of the data frame in which theMAC-d PDU was received is maintained.
 3. The method according to claim2, wherein in response to receiving the discard indication signal, theradio base station discards any MAC-d PDU still in the buffer andassociated with the data frame sequence number in the discard indicationsignal.
 4. The method according to claim 1, wherein the two octets arethe third and fourth octets following the New IE Flags field.
 5. A radiobase station, said radio base station configured to participate inmulti-point High Speed Downlink Packet Access, HSDPA, operation whereindata is communicated to a first user equipment via the radio basestation and at least one other radio base station, the radio basestation comprising: a receiver arranged to receive Medium Access Controlprotocol handling dedicated data Protocol Data Units, MAC-d PDUs, from aradio network controller in data frames, wherein each data frameconveying MAC-d PDUs is associated with a sequence number; and digitaldata processing circuitry operable connected to the receiver andarranged to buffer the received MAC-d PDUs in a buffer pending transferto the first user equipment; wherein the receiver is further arranged toreceive a discard indication signal from the radio network controller,wherein said discard indication signal includes a data frame sequencenumber and wherein the discard indication signal indicates to the radiobase station that MAC-d PDUs received by the radio base station in adata frame associated with said sequence number can be discarded;wherein the discard indication signal is a High Speed Downlink SharedChannel, HS-DSCH, DATA FRAME including a first data frame sequencenumber and a discard flag indicating that MAC-d PDUs received by the atleast one radio base station in the data frame associated with the firstdata frame sequence number can be discarded; and wherein the HS-DSCHDATA FRAME includes a New Information Element, IE, Flags field, whereinthe New IE Flags field indicates that the discard flag and the firstdata frame sequence number are present in the HS-DSCH DATA FRAME and thediscard flag and the first data frame sequence number are included intwo octets following the New IE Flags field.
 6. The radio base stationaccording to claim 5, wherein the digital data processing circuitry isadapted to, when buffering the received MAC-d PDUs in the buffer,maintain the association between each MAC-d PDU and the data framesequence number of the data frame in which the MAC-d PDU was received.7. The radio base station according to claim 5, wherein the digital dataprocessing circuitry is adapted to, in response to the receiverreceiving the discard indication signal, discard any MAC-d PDU still inthe buffer and associated with the data frame sequence number in thediscard indication signal.
 8. The radio base station according to claim5, wherein the discard flag and the first data frame sequence number areincluded in a header portion of the HS-DSCH DATA FRAME.
 9. The radiobase station according to claim 5, wherein the discard indication signalis a control frame including the first data frame sequence numberindicating that MAC-d PDUs received by the at least one radio basestation in the data frame associated with the first data frame sequencenumber can be discarded.
 10. The radio base station according to claim5, wherein the two octets are the third and fourth octets following theNew IE Flags field.